Welding Tips and Tricks

I am a beginning MIG welder and just made my first project - a 48" x 48" welding table. The top is a 1/2" plate of hot rolled steel.

Should I leave the mill scale on the top? Will this ground ok if I'm clamping to the table and not my work piece?

If I should remove it, what is the best method? Grinding all that seems like a huge pain and may leave my top not flat. Remove carefully with muriatic acid?

Leave it, it slows oxidation. With regular use your table won't get rusty.

You can leave it, the downside is the mill scale will transfer some grime to your work and gloves. Grinding is a major PITA and you will likely gouge the surface. Acid washes work, but neutralizing and clean up afterwards is another mess.

You might just those it down periodically with Non-chlorinated brake cleaner, wipe with acetone, and work away. The mill scale will inhibit rust. You’re not the only welder to work on a hot rolled top.

Years ago I added a 1/2" top to my welding table and it had mill scale on it, I don't weld every day so I was more concerned with it rusting so I just left it on there, everytime I clean it a little bit more comes off. That was 10 or 15 years ago.

I like to have it clean to get a good ground between the work and table, be it third hand or clamped to the table. I like to ground the piece I'm working on, if possible, but like to know I can ground to the table and get a good ground on the work.

As far as rust, spray Boeshield T-9, it's a rust preventative. Not a bad idea to wipe it down weekly with T-9, IMO. You will never see rust on it.

Cheers,
Alan

cj737 wrote:Acid washes work, but neutralizing and clean up afterwards is another mess.

Clay and white vinegar! Works just as well as the acid and only a slightly smelly cleanup.

Build a dam around the edge of the table and just dump some white vinegar in. Leave it over night, then just pull the clay off, let it drain, give it a quick wipe with a scotch bright pad and hose off or dump a bucket of water on.

That takes mill scale off? I guess im lucky, because most of steel in Australia over 5mm is red oxide finished, no mill scale.

Demented wrote:

cj737 wrote:Acid washes work, but neutralizing and clean up afterwards is another mess.

Clay and white vinegar! Works just as well as the acid and only a slightly smelly cleanup.

Build a dam around the edge of the table and just dump some white vinegar in. Leave it over night, then just pull the clay off, let it drain, give it a quick wipe with a scotch bright pad and hose off or dump a bucket of water on.

Vinegar is an acid. And you’ve just described the whole “messy cleanup”.

For pretty thick millscale, vinegar is too weak an acid in most readily available dilutions. It will help, but it will also attack the metal surface if strong enough, left long enough, before being neutralized. And most flat plate steel with mills ale is pretty thick stuff...

I recently used a new “gel” type rust converter on a steel work table. Benefit was that it tried to convert the millscale and it became a powdery substance. That was very easy and quick to flap disk off without damaging the underlying surface. The table sits in the shop, so rust is not a prevalent as it would be outdoors.

I always weld on a stainless section of round stock on the leg of my table for a ground clamp. It won’t rust, makes a permanent strong connection for ground, and makes the entire table usable for welding. Also keeps the lead out of my way.

cj737 wrote:

Demented wrote:

cj737 wrote:Acid washes work, but neutralizing and clean up afterwards is another mess.

Clay and white vinegar! Works just as well as the acid and only a slightly smelly cleanup.

Build a dam around the edge of the table and just dump some white vinegar in. Leave it over night, then just pull the clay off, let it drain, give it a quick wipe with a scotch bright pad and hose off or dump a bucket of water on.

Vinegar is an acid. And you’ve just described the whole “messy cleanup”.

For pretty thick millscale, vinegar is too weak an acid in most readily available dilutions. It will help, but it will also attack the metal surface if strong enough, left long enough, before being neutralized. And most flat plate steel with mills ale is pretty thick stuff...

I recently used a new “gel” type rust converter on a steel work table. Benefit was that it tried to convert the millscale and it became a powdery substance. That was very easy and quick to flap disk off without damaging the underlying surface. The table sits in the shop, so rust is not a prevalent as it would be outdoors.

I always weld on a stainless section of round stock on the leg of my table for a ground clamp. It won’t rust, makes a permanent strong connection for ground, and makes the entire table usable for welding. Also keeps the lead out of my way.

Ah, thought you were talking about stringer acids like muriatic and sulfuric with the messy cleanup. Vinegar is pretty clean compared to cleaning that stuff up.

Naval jelly or something else?

I have good luck with a'coolie hat' wheel on my 9" grinder.
-c-